Improving Retrieval Augmented Language Models: Self-Reasoning and Adaptive Augmentation for Conversational Systems

Two new approaches that have emerged in this field are self-reasoning frameworks and adaptive retrieval-augmented generation for conversational systems. In this article, we’ll dive deep into these innovative techniques and explore how they’re pushing the boundaries of what’s possible with language models.

The Promise and Pitfalls of Retrieval-Augmented Language Models

Before we delve into the specifics of these new approaches, let’s first understand the concept of Retrieval-Augmented Language Models (RALMs). The core idea behind RALMs is to combine the vast knowledge and language understanding capabilities of pre-trained language models with the ability to access and incorporate external, up-to-date information during inference.

Here’s a simple illustration of how a basic RALM might work:

1. A user asks a question: “What was the outcome of the 2024 Olympic Games?”
2. The system retrieves relevant documents from an external knowledge base.
3. The LLM processes the question along with the retrieved information.
4. The model generates a response based on both its internal knowledge and the external data.

This approach has shown great promise in improving the accuracy and relevance of LLM outputs, especially for tasks that require access to current information or domain-specific knowledge. However, RALMs are not without their challenges. Two key issues that researchers have been grappling with are:

1. Reliability: How can we ensure that the retrieved information is relevant and helpful?
2. Traceability: How can we make the model’s reasoning process more transparent and verifiable?

Recent research has proposed innovative solutions to these challenges, which we’ll explore in depth.

Self-Reasoning: Enhancing RALMs with Explicit Reasoning Trajectories

This is the architecture and process behind retrieval-augmented LLMs, focusing on a framework called Self-Reasoning. This approach uses trajectories to enhance the model’s ability to reason over retrieved documents.

When a question is posed, relevant documents are retrieved and processed through a series of reasoning steps. The Self-Reasoning mechanism applies evidence-aware and trajectory analysis processes to filter and synthesize information before generating the final answer. This method not only enhances the accuracy of the output but also ensures that the reasoning behind the answers is transparent and traceable.

In the above examples provided, such as determining the release date of the movie “Catch Me If You Can” or identifying the artists who painted the Florence Cathedral’s ceiling, the model effectively filters through the retrieved documents to produce accurate, contextually-supported answers.

This table presents a comparative analysis of different LLM variants, including LLaMA2 models and other retrieval-augmented models across tasks like NaturalQuestions, PopQA, FEVER, and ASQA. The results are split between baselines without retrieval and those enhanced with retrieval capabilities.

This image presents a scenario where an LLM is tasked with providing suggestions based on user queries, demonstrating how the use of external knowledge can influence the quality and relevance of the responses. The diagram highlights two approaches: one where the model uses a snippet of knowledge and one where it does not. The comparison underscores how incorporating specific information can tailor responses to be more aligned with the user’s needs, providing depth and accuracy that might otherwise be lacking in a purely generative model.

One groundbreaking approach to improving RALMs is the introduction of self-reasoning frameworks. The core idea behind this method is to leverage the language model’s own capabilities to generate explicit reasoning trajectories, which can then be used to enhance the quality and reliability of its outputs.

Let’s break down the key components of a self-reasoning framework:

1. Relevance-Aware Process (RAP)
2. Evidence-Aware Selective Process (EAP)
3. Trajectory Analysis Process (TAP)

Relevance-Aware Process (RAP)

The RAP is designed to address one of the fundamental challenges of RALMs: determining whether the retrieved documents are actually relevant to the given question. Here’s how it works:

1. The system retrieves a set of potentially relevant documents using a retrieval model (e.g., DPR or Contriever).
2. The language model is then instructed to judge the relevance of these documents to the question.
3. The model explicitly generates reasons explaining why the documents are considered relevant or irrelevant.

For example, given the question “When was the Eiffel Tower built?”, the RAP might produce output like this:

This process helps filter out irrelevant information early in the pipeline, improving the overall quality of the model’s responses.

Evidence-Aware Selective Process (EAP)

The EAP takes the relevance assessment a step further by instructing the model to identify and cite specific pieces of evidence from the relevant documents. This process mimics how humans might approach a research task, selecting key sentences and explaining their relevance. Here’s what the output of the EAP might look like:

By explicitly citing sources and explaining the relevance of each piece of evidence, the EAP enhances the traceability and interpretability of the model’s outputs.

Trajectory Analysis Process (TAP)

The TAP is the final stage of the self-reasoning framework, where the model consolidates all the reasoning trajectories generated in the previous steps. It analyzes these trajectories and produces a concise summary along with a final answer. The output of the TAP might look something like this:

This process allows the model to provide both a detailed explanation of its reasoning and a concise answer, catering to different user needs.

Implementing Self-Reasoning in Practice

To implement this self-reasoning framework, researchers have explored various approaches, including:

1. Prompting pre-trained language models
2. Fine-tuning language models with parameter-efficient techniques like QLoRA
3. Developing specialized neural architectures, such as multi-head attention models

Each of these approaches has its own trade-offs in terms of performance, efficiency, and ease of implementation. For example, the prompting approach is the simplest to implement but may not always produce consistent results. Fine-tuning with QLoRA offers a good balance of performance and efficiency, while specialized architectures may provide the best performance but require more computational resources to train.

Here’s a simplified example of how you might implement the RAP using a prompting approach with a language model like GPT-3:

import openai
def relevance_aware_process(question, documents):
    prompt = f"""
    Question: {question}
    
    Retrieved documents:
    {documents}
    
    Task: Determine if the retrieved documents are relevant to answering the question.
    Output format:
    Relevant: [True/False]
    Relevant Reason: [Explanation]
    
    Your analysis:
    """
    
    response = openai.Completion.create(
        engine="text-davinci-002",
        prompt=prompt,
        max_tokens=150
    )
    
    return response.choices[0].text.strip()
# Example usage
question = "When was the Eiffel Tower built?"
documents = "The Eiffel Tower is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower. Constructed from 1887 to 1889 as the entrance arch to the 1889 World's Fair, it was initially criticized by some of France's leading artists and intellectuals for its design, but it has become a global cultural icon of France."
result = relevance_aware_process(question, documents)
print(result)

def knowledge_gate(context, retrieved_knowledge=None):
    # Analyze the context and retrieved knowledge
    # Return True if external knowledge should be used, False otherwise
    pass
def generate_response(context, knowledge=None):
    if knowledge_gate(context, knowledge):
        # Use retrieval-augmented generation
        return generate_with_knowledge(context, knowledge)
    else:
        # Use standard language model generation
        return generate_without_knowledge(context)

 
import torch
from transformers import AutoTokenizer, AutoModelForSequenceClassification
class RAGate:
    def __init__(self, model_name):
        self.tokenizer = AutoTokenizer.from_pretrained(model_name)
        self.model = AutoModelForSequenceClassification.from_pretrained(model_name)
        
    def should_use_knowledge(self, context, knowledge=None):
        inputs = self.tokenizer(context, knowledge or "", return_tensors="pt", truncation=True, max_length=512)
        with torch.no_grad():
            outputs = self.model(**inputs)
        probabilities = torch.softmax(outputs.logits, dim=1)
        return probabilities[0][1].item() > 0.5  # Assuming binary classification (0: no knowledge, 1: use knowledge)
class ConversationSystem:
    def __init__(self, ragate, lm, retriever):
        self.ragate = ragate
        self.lm = lm
        self.retriever = retriever
        
    def generate_response(self, context):
        knowledge = self.retriever.retrieve(context)
        if self.ragate.should_use_knowledge(context, knowledge):
            return self.lm.generate_with_knowledge(context, knowledge)
        else:
            return self.lm.generate_without_knowledge(context)
# Example usage
ragate = RAGate("path/to/fine-tuned/model")
lm = LanguageModel()  # Your preferred language model
retriever = KnowledgeRetriever()  # Your knowledge retrieval system
conversation_system = ConversationSystem(ragate, lm, retriever)
context = "User: What's the capital of France?\nSystem: The capital of France is Paris.\nUser: Tell me more about its famous landmarks."
response = conversation_system.generate_response(context)
print(response)